Strategic Overview
- Status
- Patched in 3.5.2
- Affected Plugin
- wp-mpdf
- Affected Version
<= 3.5.1- CVSS
- 4.3Medium
- Weakness type
- CWE-352 · Cross-Site Request Forgery (CSRF)
- CVE
CVE-2021-4416
At a glance
CVE-2021-4416 is a medium-severity Cross-Site Request Forgery (CSRF) vulnerability in the wp-mpdf WordPress plugin, affecting versions <= 3.5.1. It carries a CVSS score of 4.3 (reachable over the network; low attack complexity). Exploitation requires no authentication. The issue is fixed in version 3.5.2; sites on affected versions should update now. Disclosed June 2021, reported by Jerome Bruandet.
Vulnerability Overview
The wp-mpdf plugin for WordPress is vulnerable to Cross-Site Request Forgery in versions up to, and including, 3.5.1. This is due to missing or incorrect nonce validation on the mpdf_admin_savepost() function. This makes it possible for unauthenticated attackers to save post data via a forged request granted they can trick a site administrator into performing an action such as clicking on a link.
Technical Analysis
The vector marks this flaw as remotely reachable over the network, with low attack complexity — no special timing or configuration is needed, and no privileges on the target site.
CWE-352: Cross-Site Request Forgery (CSRF)
wp-mpdf <= 3.5.1 carries this weakness at mpdf_admin_savepost(), and reaching it takes a caller who can reach the endpoint. Cross-site request forgery abuses the fact that browsers attach a victim's cookies to any request, so a state-changing action that only checks who you are, not whether you meant to act, can be triggered from another site.
An attacker who gets a logged-in user to load a crafted page can perform that action as them, with the impact scaling to whatever the victim's role is allowed to do. For wp-mpdf the fix is 3.5.2: builds <= 3.5.1 are affected, anything from 3.5.2 onward is not.
Remediation
Update to version 3.5.2, or a newer patched version
How does WordSec protect against this?
The attempt arrives as an ordinary request to wp-mpdf: WordSec's web application firewall inspects request payloads before WordPress loads them. None of that substitutes for the fix: wp-mpdf 3.5.2 closes this, and updating the plugin is the step that ends it.
- Firewall
- Alerts
External References
Related records
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